Personal management of fluid consumption is important in a wide variety of circumstances. A variety of physiological and medical problems can arise with inappropriate fluid intake. For example, under-hydration increases the risk of thermal and cardiovascular strain and heat illness, reduces heat tolerance, reduces aerobic exercise capacity and performance, and possibly increases risk of infection. Gross overdrinking can lead to hyponatremia (low blood sodium levels) or clinical problems in some patient groups such as those undergoing hemodialysis. In addition, fluid intake management takes on nutritional and clinical importance when water containing micronutrients such as salt, or macro-nutrients such as carbohydrates, are being consumed. The ability to titer or control the consumption of pharmacologically active fluids to achieve a desired outcome could have significant clinical value.
Currently, quantifying the pattern and amount of fluid consumed over time by an individual is typically a tedious and inaccurate process. One approach is to ask individuals to only drink from a given personal container, to keep track of fluid consumed from that container, and to carefully make logbook records of the date, time, and amount of liquid consumed. The volume consumed is derived by reading the liquid level from graduations on a fluid container before and after drinking and calculating the difference by mental arithmetic. This approach is difficult under low-light conditions, and incorrect logbook entries are common.
Another problem presented by currently available devices, is inaccurate or inconsistent measurements, particularly at very low flow rates. Often at low flow rates, similar to rates produced by small or gentle sips, the amount of fluid consumed is insufficient to fully engage the measurement apparatus. For example, in many currently gear or turbine type metering systems, very low fluid consumption fails to turn the gear or turbine. In these instances, the fluid fails to properly turn the gear or turbine and simple flows through or past the measurement apparatus. This leads to inaccurate fluid measurement.